Stroke is the third leading cause of death and leading single cause of disability in the United States. The estimated direct and indirect costs of stroke for 2008 are about $65 billion. It is known from prior research that early recogniton and treatment reduces the morbidity and costs associated with stroke. Thrombolysis with intravenous tissue plasminogen activator (IV t-PA) remains the only proven treatment for acute ischemic stroke who present within three hours of symptom onset with no established contraindication. However, it is also known that the rate of t-PA use in ischemic stroke patients is only 2-3%. Large scale studies have shown that poor rates of thrombolysis are due to lack of patient recognition of stroke symptoms, delay in accessing Emergency Medical Services (EMS) and in-hospital delays like lack of expedited triage.Therefore, it is well known scientifically that a multi-disciplinary approach is necessary to improve the rate of t-PA use in eligible acute stroke patients. In addition to improving knowledge on early stroke recognition in the community, the Brain Attack Coalition (BAG) determined that two levels of stroke care i.e primary and comprehensive stroke centers be created to improve emergency and other types of clinical care for stroke. With establishment of certified primary stroke centers and evidence for improved quality of care at primary stroke centers, county authorities and EMS agencies created policies to bypass the nearest emergency department and transport stroke patients to primary stroke centers. Although multiple counties are adopting the change, the impact of the policy change on regional patient outcomes has not yet been established through scientific evidence. In addition, studies on accuracy of stroke recognition by prehospital providers have shown that there is considerable scope for improvement in stroke recognition. To address these issues, I propose to conduct a study with the primary goal of studying comparative patient outcomes in regionalized and non-regionalized stroke systems. The secondary goals will be to assess the cost-effectiveness of regionalized care and accuracy of prehospital stroke recognition before and after regionalization of systems. RELEVANCE (See instructions): The study results will help to determine 1) regional differences in the rate of intravenous t-PA use and mortality among acute ischemic stroke patients 2) the impact of increasing volume in primary stroke centers and longer transport times within a regionalized system on patient outcomes.By providing evidence for patient outcomes in a regionalized stroke system.our research will provide scientific knowledge to promote health policy changes of great public health importance at a national level.